Various techniques have been developed aimed at implementing logic functions (or logic gates) in hardware. There are several different families of logic gates, including, inter alia, diode logic gates, resistor-transistor logic gates, diode-transistor logic gates, transistor-transistor logic gate, and CMOS (Complementary Metal-Oxide-Semiconductor) based logics.
For example, U.S. Pat. No. 5,012,153 discloses a split collector vacuum field effect transistor. This device is designed to perform higher level functions such as logic AND, EXCLUSIVE OR (NOR), demultiplexing, or frequency multiplication with a single device. These higher level functions are accomplished by dividing the collector of the vacuum FET into multiple segments and by providing steering electrodes just above the emitter to deflect the field emission current to the various collector segments. The collector pattern, together with the configuration of the applied signals to the device, determines the higher order function performed.
U.S. Pat. No. 5,155,420 discloses switching circuits employing field emission devices. A differential amplifier current steering circuit is described wherein the active circuit elements are realized as field emission devices (FEDs) which provide for an extended range of operation to include modulation/demodulation applications up to the order of one Terahertz and digital logic function applications up to the order of one hundred gigabits per second. In a particular embodiment of the FED, switching circuit vertical integration of selectively interconnected FEDs is employed to provide the desired switching circuit function.